1. Field of the Invention
The present application relates to implementing a planar motor. More specifically, the present application relates to methods and apparatus for initializing a planar motor with phase offsets for driving a magnet array with substantially no yaw.
2. Description of Related Art
Typical techniques for initializing a planar motor require the use of robotics and/or highly sensitive measuring equipment to initially position a magnet array above a coil array. However, such techniques can be extremely costly and subject to inefficiencies.
It is therefore desirable to provide methods and apparatus for improving the initialization of a planar motor with respect to some or all of the performance limitations noted above.
Methods and apparatus are provided for initializing a planar motor. A magnet array floating above a coil array may reside in one of a definite number of positions upon the introduction of current into the coil array. Torque characteristics of the magnet array are acquired when driving the magnet array with no phase offsets. Phase offsets for driving the magnet array with substantially no yaw can then be determined by analyzing the torque characteristics.
In one embodiment, a method for initializing a planar motor is provided. A current is provided to a coil array to drive a planar magnet array in a first direction. First torque characteristics associated with driving the planar magnet array in the first direction are determined. A first current offset is provided using the first torque characteristics for driving the planar magnet array in the first direction with substantially no yaw.
In another embodiment, a method for initializing a stage device including a planar motor that positions the stage using a position detector is provided. A current is provided to a coil array to drive a planar magnet array in a first direction. First torque characteristics associated with driving the planar magnet array in the first direction are determined. A first current offset is provided using the first torque characteristics for driving the planar magnet array in the first direction with substantially no yaw.
In another embodiment, a method for initializing a photolithography system including an illumination system that irradiates radian energy and a planar motor that positions a movable stage relative to the path of said radiant energy using a position detector is provided. A current is provided to a coil array to drive a planar magnet array in a first direction. First torque characteristics associated with driving the planar magnet array in the first direction are determined. A first current offset is provided using the first torque characteristics for driving the planar magnet array in the first direction with substantially no yaw.
In still another embodiment, a photolithography system is provided. The photolithography system includes a drive system and a detector system. The drive system is operable to provide current to a coil array to drive a planar magnet array in a first direction. The detector system is operable to determine first torque characteristics associated with driving the planar magnet array in the first direction. The drive system is further operable to provide a first current offset using the first torque characteristics for driving the planar magnet array in the first direction with substantially no yaw.
These and other features and advantages of the present invention will be presented in more detail in the following specification of the invention and the accompanying figures, which illustrate by way of example the principles of the invention.